Two-temperature refrigeration apparatus



Aug. 16, 1955 F. o. GRAHAM 2,715,319

TWO-TEMPERATURE REFRIGERATION APPARATUS Filed May 20, 1952 4 Sheets-Sheet l INVEN TOR.

BY VIM (949% Aug. 16, 1955 GRAHAM 2,715,319

TWO-TEMPERATURE REFRIGERATION APPARATUS 4 Sheets-Sheet 2 Filed May 20, 1952 IN V EN TOR.

A TTORNE Y5 Aug. 16, 1955 GRAHAM 2,715,319

TWO-TEMPERATURE REFRIGERATION APPARATUS Filed May 20, 1952 4 Sheets-Sheet 3 IN V EN TOR.

wapgwz ATTOR/VEKS Aug. 16, 1955 F. O. GRAHAM TWO-TEMPERATURE REFRIGERATION APPARATUS Filed May 20, 1952 4 Sheets-Sheet 4 76a 4-a, 3a,

73 I I 72 I INVENTOR. F19. 4 fill 0?) M w 'ffiwwq ATTORNEYS United States Patent TWO-TEMPERATURE REFRIGERATION APPARATUS Frank 0. Graham, Detroit, Mich., assignor to Temprite Products Corporation, Birmingham, Mich, a corporation of Michigan Application May 20, 1952, Serial No. 288,840

6 Claims. (Cl. 624) The invention relates to two-temperature refrigeration apparatus, the application being a continuation-in-part of application Serial No. 230,571, filed June 8, 1951, for Two-Temperature Refrigeration Apparatus, now abandoned.

The objects of the invention comprise the provision of a single-refrigerant apparatus which is capable of maintaining two independently controlled temperatures, is quickly responsive to changes in heat load, has high capacity for a given compressor size, and which is characterized by mechanical simplicity, reliable operation and moderate cost of manufacture.

For the attainment of the above stated objects and others more or less incidental or ancillary to those stated, the invention consists in combinations and arrangements of parts and features of construction defined in the appended claims and explained in the following description of exemplary embodiments of the invention which are shown in the accompanying drawings.

In the drawings,

Fig. 1 is a diagrammatic representation of apparatus embodying the invention as applied to a beverage dispenser of the type in which the beverage is formed as dispensed by mixing water and a fresh fruit concentrate.

Fig. 2 is a diagrammatic representation of an embodiment of the invention in a form suitable for a water cooler of the combined fountain and compartment type.

Fig. 3 is a diagrammatic representation of the invention showing its application to a. household refrigerator.

Fig. 4 is a diagrammatic representation of an embodiment of the invention utilizing somewhat different forms of refrigerant valve and electric switch control means than are employed in the Figs. 1-3 embodiments and having correspondingly modified operating characteristics.

Referring in detail to the apparatus illustrated and first to Fig. 1, the numeral 1 generally designates an electric-motor-driven compressor of the hermetically enclosed type. The compressor has its discharge connected to an air cooled condenser 2 and both the compressor and condenser units may be of conventional character. The compressor and condenser are operatively associated with an evaporator coil 3 which is wound parallel with a water cooling coil 4 so that the turns of the two coils are in intimate contact for heat transfer from water to refrigerant. Preferably the two coils are solder-bonded together to facilitate the heat transfer. The evaporator coil 3 has its inlet opening at the bottom of the coil connected to the discharge of the condenser 2 by a conduit 5 in the form of a restrictor tube to provide a controlled flow of liquid refrigerant from the condenser to the evaporator. The outlet passage of coil 3 at the top thereof is connected by a suction return conduit 6 with the suction inlet of the compressor 1. An accumulator 7 is interposed in the suction return line 6 and, to insure full vaporization of refrigerant discharged from Patented Aug. 16, 1955 ice coil 3, conduit 5 has a portion thereof in contact with suction return line 6 and accumulator 7. Flow of refrigerant through the suction line 6 is controlled by a solenoid valve 8 which is preferably interposed in line 6 relatively close to the discharge opening of coil 3.

Within the evaporator and water coils 3 and 4 is arranged a low-temperature evaporator coil 9 which surrounds and has intimate solder-bonded contact with the cylindrical wall of a tank 10 designed to hold a fresh fruit concentrate. The evaporator coil 9 is supplied with refrigerant through a restrictor tube 11 which has its outlet connected into the lower end of coil 9 and its inlet connected into evaporator coil 3 at an intermediate point between the bottom inlet and the top outlet of the coil. Thus refrigerant reaching coil 9 must first pass through restrictor conduit 5, the lower part of evaporator 3 and restrictor tube 11. In refrigeration systems in which the restrictor tube type of refrigerant control is employed, the liquid phase of the refrigerant charge, as is well known, is accumulated in the evaporator when the compressor is idle. Accordingly in the present apparatus during idle periods the liquid refrigerant of the system charge settles chiefly in the lower turns of evaporator coil 3; and the inlet end of the restrictor tube 11 is tapped into coil 3 at or somewhat below the top level of the liquid refrigerant in the coil. For convenience the lower turns of coil 3 which are occupied by the liquid refrigerant during idle periods may be referred to as section 3a of the evaporator while the remaining upper turns of the coil may be termed section 312.

The respective temperatures of the high temperature evaporator 3 and the low temperature evaporator 9 are controlled by starting and stopping the operation of the compressor and by opening and closing the electromagnetic valve 8, both the compressor and the valve being supplied with electric current from power lines 13 and 14 under control of thermostatic switches 15 and 16 of the adjustable snap type. Switch 15 is actuated by thermostatic bulb 15a which is in thermal contact with several turns of the water coil 4. Through the connections of its three contacts switch 15 when closed supplies current to the motor of compressor 1 and to the coil of valve 8, said valve being diagrammatically shown as of the type normally closed by gravity and which is opened when its coil is energized. Switch 16 is actuated by thermostatic bulb 16a which is arranged in thermal contact with a suitable part of the wall of tank 10. For convenience the bulb is diagrammatically shown in Fig. 1 as contacting the bottom wall of the tank. When switch 16 is closed current is supplied to the compressor motor. It will be noted that switches 15 and 16 are connected to the current source in parallel so that when either of them is in closed position, the compressor will be caused to operate and will continue to operate until both switches have opened. The solenoid valve 8 however responds only to the closing of switch 15 and regardless of the action of switch 16. By independent adjustment of switches 15 and 16 the temperature of water coil 4 and tank 10 can be controlled at will.

In the application of the invention to a beverage dispenser of the character referred to it is contemplated that the inlet end 4a of water coil 4 will be connected to :7 a source of water under pressure while the discharge end 4 b of the water coil and the discharge conduit 10a of the tank 10 will be connected with a suitable mixing valve or faucet. The supply of the fresh fruit juice concentrate in tank 10 may be renewed from time to time by an attendant. To prevent deterioration of the fresh fruit juice concentrate it is necessary that it be held at a temperature considerably lower than a suitable beverage dispensing temperature. This condition is met by the manner in which the evaporators 3 and 9 are designed and connected with the compressor, the restrictor tube between the condenser and. the evaporator 3 being designed to permit the flow of liquid refrigerant at approximately the same rate it is being liquefiedin the condenser under the conditions when evaporator 3 is supplying the load to the compressor. Restrictor tube 11 in turn is designed to further restrict the flow of liquid refrigerant such that the flow is approximately at the same rate it is being liquefied in the condenser under the conditions when evaporator 9 is supplying the load to the compressor.

'The nature ofthe apparatus will be better understood from a consideration of its operation, which comprises four conditions as follows:

Switch 15 Switch 16 Solenoid 8 Compressor 1 Operating. D0.

Not operating.

Under'condition A, upon the application of a water load switch 15 closes to open the solenoid valve and start the compressor. Under the suction of the compressor the liquid refrigerant contained in evaporator coil 3 breaks up into amixture of liquid and refrigerant vapor and, with .a suitable refrigerant charge in the system, the mixture rises in the coil so that vaporization is completed just short of the upper end of the coil. The heat load of the water coil utilizes practically the entire refrigerating capacity of the compressor which therefore operates with a comparatively high suction pressure and coring? temperature'since any evaporation which occurs in coil9'must be at the comparatively high suction pressure at which the compressor is operating.

fUndcricondition B, if the temperature of the concentrate'iri'ses above its maximum prescribed temperature and switch '16is closed while the water cooling demand remains unsatisfied, condition A will in effect prevail untillthe water cooling demand is satisfied. in other words, the water'cooling demand takes precedence at all times.

Under condition C, with no water cooling load, but with'a demand for concentrate cooling, the electromagnetic'valve will be closed and the compressor will operate' at a comparatively low suction pressure because of the high resistance of the combined restrictor tubes 5 and 11 and the reduced heat load under which the compressor operates. I

In connection with condition C it may be observed further that just prior to closing of the switch 16 the pressure in'the refrigeration system either may be equalized from unloading or the compressor dome, or crank case, may. be at a relatively high suction pressure as the .4 tity of vapor is converted into the liquid phase. This additional liquid (over and above the amount in coil 3) is first fed into coil 3 from which it flows through restrictor tube 11 into coil 9. This liquid refrigerant, added to any already in coil 9, is sufiicient in quantity to handle the moderate heat load of that coil. As the cooling of the concentrate progresses the point will be reached at which the switch 16 opens and stops the compressor. However, it before this point is reached a water-cooling demand arises, condition B will be established and concentrate cooling will be interrupted until the water-cooling demand is satisfied. 7

Under condition D, with both water cooling and concentrate cooling demand satisfied, the solenoid valve 8 will be closed and the compressor idle; and under these conditions the pressure throughout the system will be equalized and the liquid content of the coil 3 will accumulate in the lower section 3a of the coil up to the inlet of restrictor tube 11, any excess liquid finding its way into coil'9. The body of liquid refrigerant thus present in section 3a of coil 3 is'available for instant response to any sudden water cooling demand that may arise.

The design of refrigeration apparatus embodying the strictor tube 5 to balance out the high temperature evaporator with the compressor. Then the length and size of the second restrictor tube 11 is determined to give the required additional pressure drop to balance out the low temperature evaporator. with the compressor. Finally, the level at which the second restrictor tube is connected into the high temperature evaporator is determined in relation to the liquid volume of the refrigerant charge so as to effect suitable distribution of refrigerant between the two evaporators. r

In the apparatus shown in Fig. l the accumulator 7 performs the usual function of such devices in restrictor tube types of apparatus. The section 3.5 of evaporator 3 and the upper turns of evaporator'coil 9 will naturally be designed to have sufficient volumetric capacity to in sure full vaporization within the evaporators during compressor operation; however it is preferable to provide an accumulator of moderate capacity to trap overflow of liquid refrigerant from the evaporators' under unusual operating conditions and avoid undesirable frosting back.

The apparatus diagrammatically shown in Fig. 2 of the drawings represents an application of the present invention to a water cooler of the combined fountain and storage compartment type. Here the apparatus comprises a hermetic motor-driven compressor 21, condenser 22, evaporator coil 23 which is solder-bonded on the cylindrical side Wall of metal water tank 24, the lower inlet end of coil 23 being connected with condenser 22 through restrictor tube 25 and the upper discharge end of 'coil 23 being connected throughsuction conduit 26 with the'suction inlet of compressor 21. interposed in suction line 26 is an accumulator 27 and a normally closed solenoid valve 28. i

The water tank 24 has a water inlet tube 24a designed to be connected with a suitable source of water under pressure and this tube has an outlet aperture near its lower end to. discharge water against the'therrnostat well 24b which projects upwardinto the interior of the tank. The tank is also fitted with a discharge conduit 240 which may be connected with the jet nozzlev of the drinking.

fountain. The water cooler here described is disclosed in full detail in my U. S. Patent No. 2,496,466, granted February 7, 1950.

Below the water cooling evaporator 23 is arranged an evaporator coil 29 which is designed to cool the storage chamber 30 of the cooler cabinet, the outline of such chamber being diagrammatically indicated by dashed lines. The lower inlet end of coil 29 is connected by restrictor tube 31 with an intermediate point of evaporator coil 23 thus dividing the latter into a lower section 23a and an upper section 23b in a manner analogous to the division of the coil 3 of the first described apparatus into sections 3a and 3b. The upper discharge end of evaporator 29 is connected by conduit 32 with the suction return line 26 of evaporator 23 at a point between valve 28 and accumulator 27.

As in the first described apparatus, the compressor motor and the solenoid valve are energized by electric current drawn from power lines 33 and 34 under control of adjustable snap switches 35 and 36 of the thermostatic type, the switch 35 being actuated by thermostatic bulb 35a which is in thermal contact with the inner wall of well 24b of Water tank 24, while switch 36 is actuated by thermostatic bulb 36a suitably disposed in the storage chamber 30 cooled by evaporator 29.

In water coolers of the type contemplated in connection with the Fig. 2 apparatus drinking water is dispensed from the fountain at a temperature of about 40, whereas the storage compartment in the water cooler cabinet is maintained at a substantially lower temperature. In fact a portion of the storage space may be cooled to or below the freezing point to provide ice cubes.

Thus the cooling requirements of the water cooler application are closely analogous to those of the first described apparatus and the operation of the water cooler will be understood from the description of the Fig. l apparatus, the refrigeration elements of the two systems being essentially similar except for their specific forms and relative arrangements.

In the third application of the invention, shown in Fig. 3, the apparatus comprises a hermetically sealed motordriven compressor 41, condenser 42 and a high-temperature evaporator 43 which is designed to cool the main storage chamber 44 of a household refrigerator, such chamber being diagrammatically indicated by dashed lines. Here the condenser is connected to the lower in let opening of evaporator 43 by restrictor tube conduit 45 while the discharge opening of evaporator coil 43 is connected through suction conduit 46 to the suction inlet of the compressor. An accumulator 47 is interposed in conduit 46 and suction discharge from the evaporator 43 is controlled by solenoid valve 43 which is gravitybiased and normally closed. As in the previous applications the restrictor conduit 45 has contact with conduit 46 and accumulator 47 for heat interchange purposes.

The apparatus further comprises a lowtemperature evaporator 49 designed to cool a low temperature or freezing compartment 50 which is diagrammatically represented by dashed lines and is arranged above the compartment 44. The evaporator 49 is supplied with liquid refrigerant from evaporator 43 through restrictor tube 51 which is connected with an intermediate coil of the latter evaporator and opens into the lower end of evaporator coil 49. The evaporator 43 is thus divided into a lower section 43a and an upper section 431) in a manner similar to the high-temperature evaporator of the first and second embodiments of the invention. The upper discharge opening of evaporator 49 is connected by suction conduit 52 into the suction return line 46 at a point between the accumulator 47 and solenoid valve 48.

As in the earlier described applications of the invention the compressor motor and the coil of valve 48 are energized by current from power lines 53 and 54 under control of adjustable thermostatic switches 55 and 56 6 of the snap type. Switch 55 is actuated by a thermostatic bulb 55a disposed in the high-temperature chamber 44 while switch 56 is similarly actuated by thermostatic bulb 56a disposed in storage chamber 50.

As in the case of the first and second embodiments of the invention, this third form in operation is subject to the four conditions (A, B, C, D) indicated in the foregoing description of the first application and, it is believed, the operation of the third form of apparatus will be entirely clear from the description of the first form of apparatus.

In Fig. 4 the embodiment of the invention shown is a beverage cooling apparatus. generally similar to that shown in Fig. 1 and comprises hermetic motor-compressor unit 61, a condenser 62 to which the compressor discharge is connected, an evaporator coil 63, with lower turns 63a and upper turns 63b, a water coil 64 wound parallel and in intimate contact with the evaporator coil and having inlet 64a and outlet 64b, a restrictor tube 65 connecting the condenser 62 and evaporator 63, a suction return conduit 66 connecting the top of evaporator 63 to the suction inlet of the compressor and an accumulator 67, all of which parts are substantially identical with the corresponding parts of the apparatus shown in Fig. 1. However, a solenoid valve 68 which is interposed in the suction line 66 differs from the corresponding valve 8 in Fig. l in that the valve 68 is open normally, i. e., when its coil is not energized. The evaporator coil 69 and the fruit concentrate container 70 on which the coil is wound and solder-bonded are like the corresponding parts of the Fig. 1 apparatus and, as in the latter, the lower end of coil 69 is supplied with refrigerant through a restrictor tube 71 which has its inlet connected into evaporator 63 at the junction of its lower and upper turns 63a and 631). Also the upper outlet end of evaporator coil 69 is connected into suction return line 66 on the outlet side of valve 68.

In the Fig. 4 apparatus, as in that first described, the evaporator mounted on the fruit concentrate container operates at a lower pressure and temperature than does the water-cooling evaporator; and predetermined lower and upper temperatures of the two evaporators are maintained by thermostatic switch devices which automatically supply current to the compressor motor of unit 61 and the coil of valve 68 from electric power lines 72 and 73. The automatic switch devices comprise an adjustable thermostatic switch 74 and relay 75 associated with the low temperature evaporator 69 and container 70 through thermostatic switch bulb 74a and further comprise an adjustable thermostatic switch 76 associated with the high temperature evaporator 63 and water coil 64 through thermostatic switch bulb 76a. It will be seen that when the temperature of evaporator 69 and container 70 rises to a predetermined maximum, switch 74 will close to energize and close valve 68 and to energize the coil of relay 75 and start the compressor motor. The resulting work of the compressor is entirely expended in reducing the pressure in evaporator 69 because valve 68 is closed and this will continue to be the case, regardless of the pressure and temperature in evaporator 63, until the temperature of evaporator 69 is reduced to a predetermined temperature, whereupon switch 74 will open and valve 68 will open; also the compressor will stop if the temperature of evaporator 63 is below its predetermined maximum. If during the exhaustion of evaporator 69 the temperature of evaporator 63 had risen to its predetermined maximum the switch 76 would have then closed so that upon the opening of switch 74 the compressor would not stop but the application of its suction eflect would shift to evaporator 63. In other words the Fig. 4 apparatus functions in such a manner that the low temperature evaporator at all times has first call on the compressor.

It is to be understood that the kind of control means last described, which gives the low temperature evaporator first call on the compressor is not limited to the type tact form of switch used to control the soienoid valve and the compressor motor in Figs. l3 can be used in the Fig. 4 apparatus in place of the double contact switch 74 and relay 75; also that the latter switch and relay can be used in the forms of apparatus shown in Figs. 2 and 3. The double contact type of switch and the single contact relay have the advantage of very general availability and low cost.

While the fixed type of restrictor means is preferred for use it will be apparent that adjustable or variable types can be employed in the practice of the invention.

What was said relative to design considerations in connection with the first described apparatus is obviously applicable also to the second, third and fourth forms of the apparatus.

It will be seen from the foregoing description that in each form of application the apparatus provides means for definitely maintaining two different temperatures which may be varied by adjustment of the control switches, that the accumulation of liquid refrigerant in the lower section of the high-temperature evaporator renders the apparatus quickly and efiectively responsive to any increase in heat load on the high-temperature evaporator whenever the solenoid control valve is open, that in the operation of the apparatus the compressor'in large part operates with high suction pressure and with correspondingly high volumetric capacity. It is'also apparent that the improved apparatus, in its preferred form. attains the noted advantages with the use ofsimple and reliable restrictor tube and thermostatic switch control means both of which are used extensively in the refrigeration industry and are therefore available at the low cost characteristic of mass production products; It should be noted also that the valve means for giving one of the evaporators preference or first call on the suction effort of the compressor consists of a single automatic valve of simple construction and reliable operation. Furthermore, a failure of the valve to close perfectly cannot very seriously affect the operation of the apparatus. It is noted further that the apparatus is characterized by design flexibility in that the high-temperature and low-temperature evaporators may be positioned in any desired spacial relation to each other. Thus in the Fig. 1 and the Fig. 4 forms of apparatus the two evaporators are placed one within the other and at the same level, in the Fig. 2 apparatus the high-temperature evaporator is arranged above the low-temperature evaporator and in the Fig. 3 apparatus the high-temperature evaporator is arranged below the low-temperature evaporator.

From the foregoing explanation of the invention it will be apparent that the forms and relative arrangements of various parts thereof may be varied widely in practice of the invention within eouivalency bounds of the following claims.

What is claimed is:

1. In refrigeration apparatus of the type having compressor, condenser and expander elements connected in a closed circuit, the combination of a compressor; an

, electric motor connected to drive the compressor; a condenser connected to the refrigerant discharge of the cornpressor; a high-temperature evaporator comprising seriesconnected lower and upper sections in free communication with each other, the. lower section having a refrigerant inlet and the upper section a refrigerant ouaerga liquid refrigerant conduit comprising a restrictor means connecting the condenser to the lower section inlet of coil of the electromagnetically operated valve and each of i the said evaporator; a low-temperature evaporator; eon-j duit means comprising a restrictor means connecting the upper part of the lower section of the high-temperature evaporator to the refrigerant inlet of the low-temperature evaporator; suction conduit means connecting the refrigerant outlets of the two evaporators to the suction side of the compressor and rendering said evaporators simultaneously subject to the suction thereof; an electromagnetically operated valve controlling the suction outlet of the high temperature evaporator; and electric switch devices for controlling supply of current to the compressor motor, the said devices comprising two thermostatically controlled switches one of which is assocaited with and responsive to the temperature'of one of the two evaporators and the other of whichis similarly associated with and responsive to the temperature of the other evaporator and operatively connected to supply current to the which switches is connected to supply current to energize the motor when the evaporator temperature to which it is responsive rises to a predetermined maximum value and disconnected to cut off such current supply when said temperature fallsto a predetermined minimum value; whereby by opening the said valve when the compressor is operating the refrigerant returned to the compressor will be drawn substantially entirely from the high-temperature evaporator and by closing the valve when the compressor is operating the refrigerant returned to the compressor will be drawn wholly from the low-temperature evaporator.

2. Apparatus as claimed in claim 1 in which the electromagnetically operated valve is electrically connected to and controlled by the switch associated with the hightemperature evaporator.

'3. Apparatus as claimed in claim 1 in which the elec-V compressor; a high-temperature evaporator; a liquid r'efrigerant conduit comprising a restrictor means connecting the condenser to the high-temperature evaporator; a low-temperature evaporator; conduit means comprising restrictor means connecting the two evaporators; suction conduit means connecting the refrigerant outlets of the evaporators to the suction side of the compressor and rendering said evaporators simultaneously subject to the suctlon thereof; an electromagnetically operated valve controlling the suction outlet of the high-temperature.

evaporator to control the return flow of refrigerant from the said evaporator to the compressor; and electric switch devices for controlling supply of current to the compressor motor, the said devices comprising two thermostatically controlled switches one of which is associated with v and responsive to the temperature of one of the two evaporators and the other of which is similarly associated with and responsive to the temperature of the other evaporator and operatively connected to supply current to the coil of the electromagnetically operated valve and each of which switches is connected to supply current to energize the motor when the evaporator temperature to which it is responsive rises to a predetermined maximum value and disconnected to cut off such current supply when said temperature falls to a predetermined minimum value; whereby by opening the said valve when the compressor is operating the refrigerant returned to the compressor will be drawn substantially entirely from the high-temperature evaporator and by closing the valve when the compressor 1s operating the refrigerant returned to the compressor will be drawn wholly from the low-temperature evapora: tor.

5. Apparatus as claimed in claim 4 in which the electromagnetically operated valve is electrically connected to and controlled by the switch associated with the hightemperature evaporator.

6. Apparatus as claimed in claim 4 in which the electromagnetically operated valve is electrically connected to and controlled by the switch associated with the lowtemperature evaporator.

References Cited in the file of this patent UNITED STATES PATENTS Smilack Aug. 23, 1938 Newill Dec. 5, 1939 Brown et al. Apr. 23, 1940 Fletcher Nov. 26, 1940 Schmieding Apr. 22, 1941 Atchison Apr. 27, 1948 Atchison Nov. 23, 1948 Graham Feb. 7, 1950 

